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Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1133 AM CDT Mon Sep 09 2024

Valid 091700Z - 101200Z

Minor modifications have been made to the ongoing forecast based on
recent observations and model guidance. See the previous discussion
for greater details.

..Wendt.. 09/09/2024

.PREV DISCUSSION... /ISSUED 0150 AM CDT Mon Sep 09 2024/

...Synopsis...
Broad trouhging over the Northwest should continue today as an
embedded perturbation moves eastward over the northern Rockies.
Southwesterly flow aloft is forecast to increase over much of the
West as the broad trough slowly shifts east. At the surface, a cold
front will move into the Rockies, bringing a cooler air mass to
parts of the Northwest, but gusty winds to parts of the Cascades. A
lee trough developing east of the Rockies will help support isolated
dry thunderstorms over parts of WY and MT. Periods of stronger
surface winds and low RH will support elevated to near-critical
fire-weather conditions.
 
...Northwest and Great Basin....
Stronger flow aloft is expected to persist today over much of the
Northwest and northern Great Basin. Surface winds should increase to
15-25 mph as momentum from aloft mixes down. Downsloping and
mid-level drying should keep the air mass quite dry with diurnal RH
minimums below 15% likely. Several hours of widespread elevated to
near-critical fire-weather conditions are likely across the northern
Sierra and Great Basin.

Farther north, more moderate RH of 25-30% is expected beneath the
upper trough and behind the cold front. Despite the arrival of a
cooler Pacific air mass, downslope winds of 15-25 mph should overlap
with dry fuels and pockets of lower RH during the day. Overlapping
with recent lightning and fire activity, a few hours of elevated to
near-critical conditions are possible in the lee of the Cascades as
winds increase.

...Northern Rockies...
Stronger westerly flow head of the embedded shortwave will aid in
deepening a lee trough east of the Rockies. Westerly surface winds
should strengthen in turn, supporting pockets of downslope winds of
15-25 mph across parts of MT and WY. With hot temperatures and
little recent rainfall, afternoon RH values should remain quite low,
generally below 20%. Increasing winds, receptive fuels, and
persistent dry conditions should support several hours of elevated
to near critical fire-weather conditions over parts of the northern
Rockies.

...Dry Thunder...
Isolated, high-based thunderstorms appear likely over parts of the
Rockies (mainly WY and MT) today ahead of the shortwave trough. Weak
buoyancy, and PWATs of 0.5 to 0.7 inches, atop dry and well-mixed
low levels will support poor precipitation efficiency and the
potential for strong outflow winds. At least isolated storms are
expected over areas of receptive fuels. Thus, dry lightning
ignitions are possible, especially across parts of north-central WY,
where storm coverage appears greatest.

...Please see www.spc.noaa.gov/fire for graphic product...